/*
 * Copyright 2016 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#ifndef skgpu_SingleOwner_DEFINED
#define skgpu_SingleOwner_DEFINED

#include "include/private/base/SkDebug.h" // IWYU pragma: keep

#if defined(SK_DEBUG)
#include "include/private/base/SkAssert.h"
#include "include/private/base/SkMutex.h"
#include "include/private/base/SkThreadAnnotations.h"
#include "include/private/base/SkThreadID.h"

#endif

namespace skgpu {
#if defined(SK_DEBUG)

#define SKGPU_ASSERT_SINGLE_OWNER(obj) skgpu::SingleOwner::AutoEnforce debug_SingleOwner(obj, __FILE__, __LINE__);

// This is a debug tool to verify an object is only being used from one thread at a time.
class SingleOwner {
public:
    SingleOwner() : fOwner(kIllegalThreadID), fReentranceCount(0) {}

    struct AutoEnforce {
        AutoEnforce(SingleOwner *so, const char *file, int line) : fFile(file), fLine(line), fSO(so)
        {
            fSO->enter(file, line);
        }
        ~AutoEnforce()
        {
            fSO->exit(fFile, fLine);
        }

        const char *fFile;
        int fLine;
        SingleOwner *fSO;
    };

private:
    void enter(const char *file, int line)
    {
        SkAutoMutexExclusive lock(fMutex);
        SkThreadID self = SkGetThreadID();
        SkASSERTF(fOwner == self || fOwner == kIllegalThreadID, "%s:%d Single owner failure.", file, line);
        fReentranceCount++;
        fOwner = self;
    }

    void exit(const char *file, int line)
    {
        SkAutoMutexExclusive lock(fMutex);
        SkASSERTF(fOwner == SkGetThreadID(), "%s:%d Single owner failure.", file, line);
        fReentranceCount--;
        if (fReentranceCount == 0) {
            fOwner = kIllegalThreadID;
        }
    }

    SkMutex fMutex;
    SkThreadID fOwner SK_GUARDED_BY(fMutex);
    int fReentranceCount SK_GUARDED_BY(fMutex);
};
#else
#define SKGPU_ASSERT_SINGLE_OWNER(obj)
class SingleOwner {}; // Provide a no-op implementation so we can pass pointers to constructors
#endif
} // namespace skgpu

#endif
